S-(2-cyanoalkyl) phosphonothioates



United States Patent Office 3,041,365 S-(2-CYANOALKYL) PHOSPHONOTHIOATES John P. Chupp, Kirkwood, and Peter E. Newallis, Crestwood, Mo., assignors to Monsanto Chemical Company, St. Louis, Mo., a corporation of Delaware No Drawing. Filed Sept. 27, 1960, Ser. No. 58,644 7 Claims. (Cl. 260-461) wherein R is phenyl or an alkyl radical containing from 1 to carbon atoms (i.e. methyl, ethyl, propyl, but'yl, amyl, and the various isomeric forms thereof), wherein R is an alkyl radical containing from 1 to 4 carbon atoms (i.e. methyl, ethyl, propyl, butyl, and the various isomeric forms thereof), wherein X is a chalkogen of atomic weight less than 40 (i.e. sulfur or oxygen), and wherein A is a divalent aliphatic hydrocarbon radical having a chain length of two carbon'atoms connecting the cyano group and the sulfur atom and containing not more than six carbon atoms (e.g. CH CH --CH CH(CI-I CH(C H )CH etc.). As noted in copending application Serial No. 7,747 the preferred compounds for insecticidal purposes are those of the foregoing structure wherein R and R are alkyl radicals containing 1 to 3 carbon atoms.

In accordance with this invention the aforedescribed S-(Z-cyanoalkyl) phosphonothioates are prepared by reacting a phosphonothioic acid of the structure wherein R, R and X have the aforedescn'bed significance with a substantially equimolecular amount of a l-cyano substituted olefin of the structure wherein a and b are like or unlike integers from 0 to 2 (e. g. acrylonitrile, methacrylonitrile, ethacrylonitrile, propl-enyl cyanide, but-l-enyl cyanide, l-methyl prop-l-enyl cyanide, etc.). In general it is preferred that a be zero and it is particularly preferred that a and b be zero. Where desired an inert organic liquid or solvent (e.g. benzene, toluene, xylene, acetone, butanone, etc.) can be employed. While a wide range of reaction temperatures can be employed provided the system is fluid (i.e. above the freezing point of the system up to and including the boiling point of the system) it is preferred to employ a reaction temperature in the range of from about C. to about 120 C. If desired a catalyst can be employed to accelerate the reaction, the aliphatic tertiary amines (e.g. triethylamine, triisopropylamine, tributylamine, and the like) being particularly useful. Any catalytic amount can be used which amount generally will be in the range of 0.2 to 2 percent by weight of the total weight of the reactants. When and where desired a polymerization inhibitor such as hydroquinone can be used, which amount generally will be in the range of 0.05 to 4.0 percent by weight of the olefin reactant.

As illustrative of the process of this invention is the following:

2 Example I To a suitable reaction vessel equipped with a thermometer, agitator and reflux condenser is charged 15.6 parts by weight of O-ethyl methylphosphonodithioic acid, 0.3 part by weight of triethylamine, about 40 parts by weight of benzene and 0.1 part by weight of hydroquinone. While agitating this mass there is added about 5.3 parts by weight of acrylonitrile. The mass is then heated at 6080 C. for 8 hours, and then cooled to room temperature. The so-cooled reaction mass is then washed first with 5% aqueous sodium carbonate and then twice with water. 1 The so-washed mass is then subjected to vacuum distillation .to remove the benzene. The residue, 18.1 parts by weight of a yellow oil, is O-ethyl S-(Z-cyanoethyl) methylphosphonodithioate which is soluble in chloroform and acetone but insoluble in water. I

Analysis-Theory: 30.6% S, 14.8% P, ,,,6.7% N. Found: 30.2% S, 14.5% P, 6.1% N.

Example 11 Employing the procedure of Example I but replacing a insoluble in water.

Analysis-Theory: 32.8% S, 15.9% P. Found: 32.7% S, 15.4% P.

Example III Employing the procedure of Example I but replacing O-ethyl methylphosphonodithioic acid with an equimolecular amount of 'D-ethyl methylphosphonothioic acid there is obtained as a water-insoluble oil O-ethyl S-(2-cyan0-. ethyl) methylphosphonothioate.

Example IV Employing the procedure of Example I butreplacing O-ethyl methylphosphonodithioic acid with an equimolecular amount of O-methyl methylphosphonothioic acid there is obtained O-methyl S-(Z-cyanoethyl) methylphosphonothioate which is insoluble in water but soluble in acetone.

Example V Employing the procedure of Example I but replacing O-ethyl methylphosphonodithioic acid with an equimolecular amount of O-isopropyl phenylphosphonodithioic acid there is obtained O-isopropyl S-(Z-cyanoethyl) phenylphosphonodithioate which is soluble in acetone but insoluble in water.

Example V1 Employing the procedure of Example I but replacing acrylonitrile with an equimolecular amount of methacrylonitrile there is obtained O-ethyl S-(Z-cyanopropyl) methylphosphoncdithioate, and oil which is soluble in acetone but insoluble in water.

Example VII Employing the procedure of Example I but replacing acrylonitn'le with an equimolecular amount of prop-l-enyl cyanide there is obtained O-ethyl S-(l-methyl-Z-cyanoethyl) methylphosphonodithioate, an oil which is soluble r certain embodiments it is not so limited and it is to be Patented June 26, 1962 understood that variations and modifications thereof obvi- 3. The method of claim 1 wherein the l-cyano subous to those skilled in the art can be made without destituted olefin reactant is acrylonitrile. parting from the spirit or scope of this invention. This 4. The method of making O-alkyl S-(Z-cyanoethyl) application is a continuation-impart of copending applialkylphosphonothioates which comprises reacting acrylocation Serial No. 7,747, filed February 10, 1960. 5 nitr-ile with a substantially equimolecular amount of a What is claimed is: a phosphonothioic acid of the structure 1. The method of making 8- (Z-cyanoalkyl) phosphonothioates of the structure 7 (alkyl) a stituted olefin reactant is wherein R isselected from thegroup consisting of phenyl and alkyl radicals co'ntaining'l to carbon atoms, wherein R is an, alkyl radical. containing from 1 to 4 carbon atoms, whereX is a chalkogen of atomic weight less than 40, and wherein A is a divalent aliphatic hydrocarbon radical having a chain length oftwo carbon atoms connecting the sulfur atom and the cyano group and containing not .3 atoms which comprises reacting a lonitrile with a substantially equimolecular amount of 0- Phosphonothlolc of the Stmoture ethyl methylphosphonodithioic acid in the presence of a R'O X catalytic amount of triethylamine.

\il 7. The method of making O-alkyl S-(2-cyanoethyl) alkylphosphonodithioates which comprises reacting acry- R lonitrile with a substantially equimolecular amount of 3. wherein R, R and X have the aforementioned significance phosphonodithioic acid of the structure with a substantially equimolecular amount of a l-cyano wherein X is a chalkogen of atomic weight less than 40 and wherein the respective alkyl snbstituents contain from 1 to 3 carbon atoms.

5. The method of claim 4 wherein X is sulfur, the method being carried out in the presence of a catalytic amount of an aliphatic tertiary amine.

6. The method of making O-ethyl S-(Z-cyanoethyl) methylphosphonodithioate which comprises reacting acrysubstituted olefin of the structure (alkyD-O s H(orn).-or'r=o-oN r t EL I V i)b 27 wherein a and bare integers from 0 to 2. v

The method f claim, -1 wherein the Layne wherein the respective alkylsubstituents contain from to 3 carbonatoms. CH:=(3CN wherein "b is an integer from fi to 2.

No references cited. 

1. THE METHOD OF MAKING S-(2-CYANOALKYL) PHOSPHONOTHIOATES OF THE STRUCTURE 